Method and device for embossing of a nanostructure

ABSTRACT

A method for embossing a nanostructure, formed on a nanostructure punch, into a punch surface of a curable material which has been applied to a substrate. The method includes the following steps, especially following sequence: alignment of the nanostructure relative to the punch surface, embossing of the punch surface by a) prestressing of the nanostructure punch by deformation of the nanostructure punch and/or prestressing of the substrate by deformation of the substrate, b) making contact of a partial area of the punch surface with the nanostructure punch and c) automatic contacting of the remaining surface at least partially, especially predominantly, by the prestressing of the nanostructure punch and/or the prestressing of the substrate.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 16/654,098,which is a continuation of U.S. application Ser. No. 16/141,059, filedSep. 25, 2018 (now U.S. Pat. No. 10,493,747, issued Dec. 3, 2019), whichis a continuation of U.S. application Ser. No. 15/113,111, filed Jul.21, 2016 (now U.S. Pat. No. 10,118,381, issued Nov. 6, 2018), which is aU.S. National Stage of International Application No. PCT/EP2014/58141,filed Apr. 22, 2014, said patent applications herein fully incorporatedby reference.

FIELD OF THE INVENTION

This invention relates to a method of embossing a nanostructure and to acorresponding device for embossing a nanostructure.

BACKGROUND OF THE INVENTION

Nanoimprint lithography (NIL) is a forming method in whichnanostructures are formed by a punch in curable materials, for exampleresist. In doing so not only is forming of a large number ofnanostructure systems possible, but also the production ofhigh-precision nanostructures on large areas by a step-and-repeat or aroll method. High-resolution surface structuring can be carried out withit. Fundamentally it is distinguished between thermal NIL (hot-embossingNIL) and UV-based NIL methods.

Based on the viscosity of the photoresist, capillary action cancompletely fill the intermediate spaces of the punch with it. In UV-NILthe punch at room temperature is pressed into the flowable resist, whilein thermal NIL methods the thermoplastic resist must be pressed into theresist at elevated temperature (above the glass transition temperature).The punch is removed only after the cooling. In UV-NIL lower contactpressures can be used and the process can take place at roomtemperature. The UV resist cross-links when exposed to UV radiation intoa stable polymer (curing). Therefore structuring can be carried out with“soft” polymer punches and with hard punches. The soft UV-NIL withpolymers as the punch materials, depending on the application, is anoften economical alternative to structuring with hard punches. SoftUV-NIL (therefore with polymer punches) is also carried out with hardpolymer punches. The modulus of elasticity of quartz is roughly 100 GPa.In comparison, the moduli of elasticity of polymers (hard and softpolymers) are up to several orders of magnitude smaller, therefore theyare called “soft” compared to quartz (soft lithography).

The most important parameters in the NIL methods are the temperature(mainly in hot-embossing NIL), the contact pressure and the adhesionbetween the resist and punch. In order to reduce high adhesion betweenthe resist and punch, the punch surface should have a surface energy aslow as possible—in interplay with the resist.

Depending on the application, the 3-D structured resist itself can beused as a functional unit or is used as a mask for following etchingsteps.

For large areas it is difficult to distribute the pressure uniformlyover the entire contact surface and to compensate for irregularities.Therefore nonuniform structuring can occur. In order to carry out thestructuring of larger areas, embossing is done with a roller oralternatively the entire surface is gradually structured with a smallerpunch by shifting the punch (step-and-repeat method).

Nanoimprint is used to produce multilayer structures and (economical)nanostructures (for example integrated circuits in silicon technology)with a resolution below the diffraction limit of light. A large-areanano-embossing process on the entire wafer allows costs, effort and timeconsumption to be kept low.

Embossing defects which can occur in NIL are for example cracks,nonuniformly filled punch structures (therefore for example airinclusions) and a nonuniform resist layer thickness. The adhesionbetween the resist and punch is critical. Otherwise distortions orcracks occur. Soft and also hard punches can deform by the appliedpressure during the NIL process. Furthermore (dirt) particles are verycritical. Particles which are located between for example the resist andpunch lead to defects in the entire periphery of the particle.

High-resolution structuring in the low nm range (50 nm) is one of themost important advantages of NIL. The replication of structures in thesub 20 nm range is however still a challenge.

Often, for larger wafers, several embossing steps in succession must becarried out to achieve the desired dimensional accuracy. The problemwith these embodiments is however ensuring an exact alignment of themany embossing steps with the punch. Generally alignment marks which arelocated on the substrate and/or on the punch are used. High-precision,aligned embossing of different layers on top of one another is notpossible or is possible only with great effort.

SUMMARY OF THE INVENTION

The object of this invention is to devise a method and a device forembossing of a nanostructure with which large-area substrates can beembossed as much as possible without repeating process steps withstructures which are as small as possible.

This object is achieved with the features of the independent claim(s).Advantageous developments of the invention are given in the dependentclaims. All combinations of at least two of the features given in thespecification, the claims and/or the figures also fall within the scopeof the invention. At the given value ranges, values which lie within theindicated limits will also be considered to be disclosed as boundaryvalues and will be claimed in any combination. To the extent featuresdisclosed for the device can also be interpreted as features of themethod, they should also be considered as according to the method andvice versa.

The basic idea of this invention is to make contact first with only apartial area of a punch surface with the nanostructure punch byprestressing a nanostructure punch and/or a substrate and then to effectautomatic contact-making with the contact surface by releasing thenanostructure punch, preferably the entire punch area being embossedwithout repeating the aforementioned steps.

The invention relates in particular to an installation and a method forcarrying out a large-area UV-NIL nanoembossing process with a hardnanostructure punch.

The invention relates in particular to equipment and a method forcarrying out a large-area nanoembossing process. The large-areananoimprint process (up to 18″ substrates or more) is carried out with ahard UV-transparent nanostructure punch—typically in wafer format. Indoing so the structured nanostructure punch makes contact with asubstrate to which resist has been applied beforehand over the entiresurface. The resist can be applied separately from the embossing processin its own module. The imprint takes place especially under a vacuum orat ambient pressure in an inert gas atmosphere. The embossing front canalternately be started with an actuator in the center or substrate edge.The structured punch surface can be impressed in the curable material,especially resist, on the substrate and the structures of thenanostructure punch can be replicated by the propagation of theembossing front. The process can preferably be used for embossing afirst layer or a second layer in combination with exact alignment(SmartView Alignment).

The invention can be used in combination with the established industrialresist application methods, such as for example spin coating methods.The resist can be applied separately from the embossing process in itsown module. Thus the application of the resist to the substrate is fast,free of defects, blanketing, free of particles and standardized; thisalso entails throughput advantages in the embossing step. Embossing inthe vacuum or at ambient pressure under inert gas is possible forreduced embossing defects (for example air inclusions, etc.) and easierseparation between nanostructure punch and substrate. One importantadvantage of this new technology is that substrates to which resist hasbeen applied in a blanket manner can also be contacted at ambientpressure without defects.

Other advantages include the following:

-   -   no distortion,    -   replication of structures in the sub 10 nm range,    -   combination with alignment for high-precision, aligned embossing        of different layers on top of one another, for example with the        aid of the SVA (SmartView® Alignment) method, and    -   higher resolution is possible.

The invention relates in particular to a method and a device fortransfer of a structure, in particular a microstructure or morepreferably a nanostructure from a UV-transparent nanostructure punch toone flat side of a resist-blanketed substrate with a substrate palletwhich holds the substrate on a substrate chucking surface, a structuresurface of the nanostructure punch which can be aligned parallel to thesubstrate chucking surface and which can be arranged opposite it, andwith an actuator which acts orthogonally to the substrate chuckingsurface and to the structure surface of the nanostructure punch.

The invention is based on a large-area nanoimprint process by means of ahard UV-transparent punch. The nanostructure punch can also betransparent to other ranges of electromagnetic radiation. A wafer isdefined as a substrate or product substrate, for example a semiconductorwafer. Substrates with a hole such as HDDs are also intended. Theproduct substrates can also be bilaterally structured or processedproduct substrates. The substrate can have any shape, preferably round,rectangular or square, more preferably in the wafer format. The diameterof the substrates is more than 2 inches, preferably more than 4 inches,more preferably more than 6 inches, still more preferably more than 8inches, most preferably more than 12 inches, most preferably of all morethan 18 inches. Square glass substrates have dimensions of 5 mm×5 mm to20 mm×20 mm or larger. Rectangular glass substrates have dimensions of 5mm×7 mm to 25 mm×75 mm or larger. The nanostructure punch can have anyshape, preferably round, rectangular or square, more preferably thewafer format. The diameter of the nanostructure punch preferably largelyagrees with the diameter of the substrates.

The nanostructure punches are preferably formed from hard UV-transparentmaterials such as quartz/silicon dioxide, more preferably they areUV-transparent polymer punches such as among other polydimethylsiloxane,polytetrafluorethylene, perfluorinated polyether, polyvinyl alcohol,polyvinyl chloride, ethylene tetrafluorethylene, most preferably theyare hard UV-transparent polymers. The punch material of the presentinvention in UV curing of the embossing material on the substrate ispreferably at least partially transparent to the wavelength range of theelectromagnetic radiation which cross-links the embossing material. Theoptical transparency is especially greater than 0%, preferably greaterthan 20%, more preferably greater than 50%, most preferably greater than80%, most preferably of all greater than 95%. The wavelength range forthe optical transparency is especially between 100 nm and 1000 nm,preferably between 150 nm and 500 nm, more preferably between 200 nm and450 nm, most preferably between 250 nm and 450 nm.

The UV-transparent and/or IR-transparent nanostructure punch can haveany shape, preferably round, rectangular or square, more preferably awafer format. The diameter of the nanostructure punch preferablyessentially agrees with the diameter of the substrates. Thenanostructure punch can have a positive and/or negative profilinglocated on the side facing the substrate surface which is to be treated.

The deposition/contacting of the substrate and the nanostructure punchis especially critical since faults can occur here, and the faults canadd up and thus reproducible alignment accuracy cannot be maintained.This leads to considerable scrap. In the critical step of contact-makingof the aligned contact surfaces of the substrate and the nanostructurepunch more and more exact alignment accuracy or offset of less than 100μm, especially less than 10 μm, preferably less than 1 μm, mostpreferably less than 100 nm, most preferably of all less than 10 nm isdesirable. At these alignment accuracies many influencing factors mustbe considered.

The device of this invention can be regarded as a development of thedevices which were mentioned the first time in patent AT405775B.AT405775B describes a method and a device for aligned joining ofwafer-shaped semiconductor substrate. In the new device of the presentinvention the substrate and nanostructure punch are joined aligned sothat approach and alignment for a nanoimprint embossing process with ahard punch are carried out in a controlled manner. The installationpreferably has a system for contactless wedge fault compensation betweenthe punch and substrate which are aligned parallel (seeWO2012/028166A1).

The invention is based especially on the idea of the substrate andnanostructure punch making contact in a manner as coordinated andsimultaneous as possible, more or less automatically, by at least one ofthe two, preferably the nanostructure punch, being exposed, beforemaking contact, to prestressing which runs especially concentrically tothe middle M of one contact surface of the nanostructure punch radiallyto the outside and then only the start of making contact beinginfluenced, while after making contact with one section, especially themiddle M of the punch, the nanostructure punch is released andautomatically embosses the opposite substrate in a controlled mannerbased on its prestress. The prestress is achieved by a deformation ofthe nanostructure punch by deformation means, the deformation means inparticular based on their shape acting on the side facing away from theembossing side and the deformation being controllable accordingly by theuse of different, interchangeable deformation means according toapplication WO2013/023708A1. Control takes place by the pressure or theforce with which the deformation means are acting on the nanostructurepunch.

The device can advantageously also be operated in a vacuum or even atambient pressure under inert gas, as a result of which advantageouslyembossing defects such as for example air inclusions are avoided. If thedevice is operated in a vacuum, the pressure is less than 500 mbar,preferably less than 100 mbar, most preferably less than 10 mbar, mostpreferably of all less than 1 mbar.

A preferably present gas atmosphere can dampen the contact-makingprocess and thus prevent the contact surfaces from coming into contactprematurely or at different sites at the same time, which would lead todistortions. On the other hand gas inclusions can occur. Therefore it isnecessary and feasible to optimize the process and in particular matchthe ambient pressure during contact-making to the circumstances of thesubstrates and nanostructure punch.

One very frequently used type of fixing of the substrate andnanostructure punch on the respective wafer chuck takes place using avacuum or negative pressure. The substrate and nanostructure punch arefixed on a flat hardened surface in which vacuum tracks are milled, bynegative pressure or vacuum. The wafer chuck (substrate chuckingapparatus) for the substrate has vacuum tracks on the entire surface oron the outer zones of the surface. Advantageously the negative pressurechannel runs concentrically, in particular circularly, to a center Z ofthe chucking apparatus, in particular around the entire periphery. Thisyields uniform fixing. Furthermore, if necessary the contour of thechucking surface can be set back relative to the chucking plane of thechucking surface so that depressions are formed which diminish or changethe support surface. Thus bilaterally structured or processed substrates(product substrates) can also be used.

The wafer chuck for the nanostructure punch has in particular a hole forthe actuator and vacuum tracks in the edge region. Here there is atleast one negative pressure channel which interrupts the chuckingsurface in the outer ring section of the chucking contour. As necessary,the chucking surface of the chucking apparatus can be reduced so that asmaller contact surface between the substrate and wafer chuck arises.

Other possibilities of fixing of the substrate and nanostructure punchon the respective wafer chuck are mechanical fixing by clamping orelectrostatic fixing. Wafer chucks with pins (pin chucks) are used.Special adhesives can also be used.

One embodiment of the substrate chucking apparatus of the presentinvention moreover enables the handling of substrates, especiallywafers, with a liquid layer on top. The liquid layer is especially aliquid embossing resist which is located in the interface duringcontact-making.

The resist can be applied in particular separately from the embossingprocess in its own module. Thus standardized resist application methodscan be used under controlled conditions; this entails throughputadvantages in the subsequent embossing step. The substrate is blanketedbeforehand with a nanoimprint resist in a resist application chamber.The layers are applied especially with spin, spray or inkjet methods andimmersion coating or roller coating methods. Alternately the solvent isthen vaporized and the wafer is transferred to an embossing chamber.

Materials for the substrate surface or substrate coating which is to beembossed can be especially UV-hardenable substances or thermallyhardenable substances such as polymers or resists. In UV nanoimprintlithography the nanostructure punch at room temperature is pressed intothe flowable resist while in thermal methods the thermoplastic resist ispressed into the resist at elevated temperature. Curing takes placedepending on the resist material preferably by UV light but alsopossibly by IR light. More generally the curing can be carried out byelectromagnetic radiation, by heat, by current, by magnetic fields orother methods. The curing is preferably based on polymerization of thebase material. In doing so the polymerization is started by a so-calledinitiator.

An additional antiadhesion coating or the application of an adhesive orthe application of a separating agent on the nanostructure punch areprovided according to one advantageous embodiment. The nanostructurepunch is coated with an antiadhesion layer in order to additionallyreduce the adhesion between the nanostructure punch and substratecoating (embossing mass). Preferably the antiadhesion layer is organicmolecules with correspondingly low adhesion properties to the substratecoating. The layer thickness of the coating is especially less than 1mm, preferably less than 100 μm, more preferably less than 10 μm, mostpreferably less than 1 μm, most preferably of all less than 100 nm, evenmore preferably less than 10 nm. A small layer thickness has abeneficial effect on the transmission of the electromagnetic radiationwhich is used for example for UV curing. Separation agents are forexample self-organized monolayers (SAM) or multilayers. Surfaceactivation by means of plasma would be conceivable as a furtherpretreatment step.

By integration of a lamp housing in one embodiment of the device of thepresent invention, exposure is carried out with UV light, especiallythrough the nanostructure punch, in order to enable curing of theembossing resist with UV light. The nanostructure punch and optionallyalso other bordering components of the punch mount are made of UV-and/or IR-transparent materials.

The substrate and the nanostructure punch are kept separate during theevacuation and/or inert gas flushing process, the transparentnanostructure punch being held at the top (structured side down) and thesubstrate at the bottom. The deformation of the nanostructure punch iscontrolled by the pressure or the force with which the deformation meansare acting on the nanostructure punch. It is advantageous here to reducethe effective chucking area of the chucking apparatus with thenanostructure punch so that the nanostructure punch is only partiallysupported by the chucking apparatus, preferably is supported only on theedge. In this way the smaller contact area on the edge yields loweradhesion between the nanostructure punch and the punch mount or thepunch chucking apparatus. This enables careful and reliable detachmentof the nanostructure punch, with detachment forces which are as small aspossible. The detachment of the nanostructure punch is thuscontrollable, especially by reducing the negative pressure on thechucking surface.

The nanoimprint process is preferably initiated with an actuator (pin),alternately in the substrate center M or substrate edge R. In doing sothe UV-transparent nanostructure punch is locally bent with the actuator(deformation) in order to define the first contact point (partial areaof the punch surface) with the liquid embossing resist on the substrate.After the first contact point has been reached, the pressure on thevacuum tracks of the punch chucking apparatus is interrupted, orespecially separately for each vacuum track, reduced so that the punchis released and the embossing front can run independently over theentire punch surface. The vacuum tracks of the upper wafer chuck arepreferably located in the edge region so that the detachment from thenanostructure punch is carried out in a controlled manner, especially byreducing the negative pressure on the chucking surface. Only bycontrolled reduction of the negative pressure is detachment of thenanostructure punch from the punch chucking apparatus, especially fromthe edge region, effected.

First, the transparent nanostructure punch is loaded especially on thetop side wafer chuck (punch chucking apparatus) and detected with analignment system. Afterward the resist-coated substrate is loaded andthe two wafers are aligned with high precision with an alignment systemfor exact alignment. Patent DE102004007060 B3 describes a device and amethod for joining two wafers, or any type of flat component which is tobe aligned, along their corresponding surfaces. In doing so the wafersare exactly aligned. The device for nanoimprint embossing has similarfeatures, here one substrate and one nanostructure punch at a time beingexactly aligned: a) a first apparatus for chucking and aligning ananostructure punch (punch chucking apparatus), b) a second apparatusfor chucking and aligning a substrate relative to the nanostructurepunch (substrate chucking apparatus).

The contact surfaces make contact and the corresponding surfaces areembossed by means of the apparatus at one embossing initiation site. Thenanoimprint embossing of the substrate with the nanostructure punchtakes place along one embossing front which runs from the embossinginitiation site to the side edges of the nanostructure punch bydetaching the nanostructure punch from the punch chucking surface.

According to one advantageous embodiment a detection apparatus (notshown) provides for exact alignment of the substrate and thenanostructure punch by its detecting the relative positions and relayingthem to the control unit which then aligns the substrate and thenanostructure punch to one another. The alignment takes place manuallyor automatically (preferably) with a misalignment of less than 100 μm,preferably less than 10 μm, still more preferably less than 1 μm, mostpreferably less than 100 nm, most preferably of all less than 10 nm.

The distance between the substrate and the nanostructure punch is thenreduced to an exactly defined distance before the nanoimprint process isstarted. In the embossing method of the present invention the substrateand the punch are not placed flat on one another, but are brought intocontact with one another first at one point, for example the middle M ofthe substrate, by the nanostructure punch being pressed lightly againstthe substrate by deformation means and in doing so being deformed. Afterdetaching the deformed, i.e. bent nanostructure punch (in the directionof the opposite substrate) a continuous and uniform embossing along theembossing front takes place by the advance of an embossing wave.

Inasmuch as the deformation means is at least one pressure element(actuator) which penetrates the chucking contour, the pressure can beapplied uniformly, especially from the center Z outward. Preferablythere is a mechanical approach especially by a pin or actuator. Otherdeformation means such as exposure to a fluid or a gas are conceivable.

In a first embodiment of the present invention the nanoimprint processis initiated with an actuator in the substrate center (middle M) and theembossing front propagates from the center, from inside to outside,toward the wafer edge. Here it is advantageous to allow the resultingforce F_(a) to act by triggering the actuator (pin) or the actuatorapparatus in the center of mass of a contact surface between thesubstrate and nanostructure punch. Here the force F_(a) is less than 100kN, preferably less than 10 kN, more preferably less than 1 kN, mostpreferably less than 500 N, most preferably of all less than 100 N,still more preferably less than 10 N.

In a second embodiment of the present invention the nanoimprint processis initiated with an actuator on the substrate edge and the embossingfront propagates away from the edge contact point R. In this embodimentthe resulting force F_(a) acts by triggering the actuator or actuatorapparatus in the surface edge region of the nanostructure punch. Byacting on the nanostructure punch on the edge of the chucking surface(on the back of the nanostructure punch) especially careful detachmentis possible.

In the two embodiments the embossing front runs at least largelyindependently over the entire punch surface, especially caused by theforce of the nanostructure punch due to weight.

Then, in one preferred embodiment the wafer stack is transferred to anunloading station and the resist is cross-linked through the transparentpunch by UV light. The embossing resist (curable material) is cured bythe UV cross-linking. The UV light used is alternately broadband lightor it is specially matched to the photoinitiator used in the embossingresist. The wavelength range of the curable material is especiallybetween 50 nm and 1000 nm, preferably between 150 nm and 500 nm, morepreferably between 200 nm and 450 nm.

At the end of the method the nanostructure punch in the embossingchamber is removed from the substrate and the substrate is unloaded.

In an installation of the present invention especially the process stepsof coating of the substrate, alignment, embossing (nanoimprintlithography), separation of the punch and substrate, and optionallyinspection (metrology) are integrated. It would be conceivable to carryout separation directly in the imprint stage, thus the punch remains inthe installation, in contrast to wafer bonding installations accordingto AT405775B, for example. The installation preferably has sensors forforce monitoring for control of the separation step. Furthermore inparticular precautions are taken to avoid static charges. The method ofthe present invention for nanoimprint embossing of substrates with ahard polymer punch therefore in one general embodiment has especiallythe following steps:

a) substrate coating or resist application, therefore application of thestructure material (resist) to the substrate by means of an applicationapparatus, for example a spin resist application installation,

b) alignment of the substrate (chucking apparatus) and nanostructurepunch (embossing apparatus) by means of an alignment apparatus,

c) embossing of the substrate by the embossing apparatus with anactuator,

d) UV exposure of the curable material and separation of thenanostructure punch and substrate.

The installation has especially one module group with a common workingspace which can be sealed if necessary relative to the ambientatmosphere. Here the modules, for example the resist application module(for spin coating, for example), imprint module and unloading module canbe arranged in a cluster or star configuration around a central modulewith one movement apparatus (robot system). The separation can takeplace directly in the imprint stage. Likewise the resist can be appliedseparately from the embossing process in its own module; this yieldsmajor throughput advantages. For reduced embossing defects and easierseparation between the punch and substrate the embossing can be carriedout on the imprint stage in the imprint module in a vacuum and/or underinert gas. The embossing under an inert gas atmosphere can yieldadvantages such as better chemical resistance, better adhesion andfaster UV hardening. Alternatively the entire working space can befilled with an inert gas and/or exposed via a vacuum apparatus to avacuum as a defined atmosphere. The application process (coating of thesubstrate) can also be carried out in the above defined atmosphere. Thusgas inclusions which arise can be largely avoided or precluded.

One important advantage of this new technology is that resist-blanketedsubstrates can be contacted without defects at ambient pressure andunder an inert gas atmosphere.

The embodiment of the installation of the present invention makespossible aligned embossing of high-resolution structures on the waferplane with a sub 200 nm alignment accuracy especially with the aid of analignment method for aligning two components, therefore the substrateand nanostructure punch.

The embodiment of the present invention in particular enablesdistortion-free and large-area embossing of high-resolution structures.One advantage of the method of the present invention is thatresist-blanketed substrates at ambient pressure can be contacted free ofdefects under inert gas. Furthermore automation of the technology ispossible so that resist application and embossing can be carried outquickly, uniformly, free of defects, and free of foreign particles.

Articles which can be produced with this method are among others harddisk drives (HDDs) of the next generation such as bit patterned media(BPM), polarizers, quantum dots, photonic structures, opticalstructures, as well as structures for sequencing (nanopores, nanodots,etc). The execution of the described methods for substrates with a hole(hard disk) will be mentioned in particular.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages, features and details of the invention will becomeapparent from the following description of preferred exemplaryembodiments and using the drawings.

FIG. 1a shows a plan view of a punch chucking apparatus of one preferredembodiment of a device of the invention with a cutting line A-A,

FIG. 1b shows a cross sectional view according to cutting line A-A fromFIG. 1 a,

FIG. 1e shows a cross sectional view of a second embodiment of theinvention,

FIG. 2a shows a plan view of a substrate chucking apparatus of onepreferred embodiment of a device of the invention with a cutting lineB-B,

FIG. 2b shows a cross sectional view according to cutting line B-B fromFIG. 2 a,

FIG. 2c shows a cross sectional view of a second embodiment of theinvention, especially for bilaterally structured product substrates,

FIG. 3a shows a plan view of a substrate chucking apparatus of a secondembodiment of a device of the invention with a cutting line C-C,

FIG. 3b shows a cross sectional view according to cutting line C-C fromFIG. 3 a,

FIG. 3c shows a plan view of a substrate with a hole, especially forproducing a hard disk,

FIG. 4a shows a plan view of a substrate chucking apparatus of a thirdembodiment of a device of the invention with a cutting line D-D,

FIG. 4b shows a cross sectional view according to cutting line D-D fromFIG. 4 a,

FIG. 5a shows a cross sectional view of the device of the invention in afirst method step of the invention,

FIG. 5b shows a cross sectional view of the device of the invention in asecond method step of the invention,

FIG. 5c shows a cross sectional view of the device of the invention in athird method step of the invention,

FIG. 6a shows a cross sectional view of the device of the invention in afourth method step of the invention,

FIG. 6b shows a cross sectional view of the device of the invention in afifth method step of the invention after the punch chuck and substratechuck approach one another,

FIG. 6c shows a cross sectional view of the device of the invention in asixth method step of the invention, in particular during the contactingof a nanostructure punch by an actuator for elastic bending of thenanostructure punch and contacting of the nanostructure punch with thesubstrate;

FIG. 6d shows a cross sectional view of the device of the invention in aseventh method step of the invention, during an advancing embossing wavealong an embossing front between the punch and substrate, thenanostructure punch being detached from a punch chucking apparatus byinterrupting the vacuum in the vacuum tracks,

FIG. 6e shows a cross sectional view of the device of the invention inan eighth method step of the invention with ended embossing front,

FIG. 7a shows a cross sectional view of the device of the invention in asecond embodiment of the method of the invention with an actuator whichis positioned centrally on the punch,

FIG. 7b shows a cross sectional view of the device of the invention in asecond embodiment of the method after the approach of the punch chuckand substrate chuck to one another,

FIG. 7c shows a cross sectional view of the device of the invention inthe second embodiment of the method during the contacting of the punchby an actuator, elastic bending of the nanostructure punch andcontact-making between the nanostructure punch with the substrate with ahole taking place by the actuator,

FIG. 7d shows a cross sectional view of the device of the invention inthe second embodiment of the method during the advancing embossing wavebetween the punch and substrate with the hole, the nanostructure punchbeing detached from the punch chucking apparatus by interrupting thevacuum in the vacuum tracks,

FIG. 7e shows a cross sectional view of the device of the invention inthe second embodiment of the method with ended embossing front,

FIG. 8 shows a cross sectional view of the substrate chucking apparatusafter embossing, the wafer stack (substrate with resting nanostructurepunch) being transferred to an unloading station and the curablematerial being cross-linked/cured in particular through the transparentpunch by means of UV light,

FIG. 9a shows a cross sectional view of one embodiment of the method ofthe invention, an actuator acting centrally on the nanostructure punchacting on the substrate and the nanostructure punch and

FIG. 9b shows one embodiment of the method of the invention, an actuatoracting at the edge of the substrate on the nanostructure punch acting onthe substrate and the nanostructure punch.

In the figures the same components and components with the same functionare identified with the same reference numbers.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1a shows a punch chucking apparatus 1 of a device for chucking of ananostructure punch 5 on a chucking body 1 k. Nanostructure punch 5 isfor embossing a nanostructure 13 that is formed on nanostructure punch5. The chucking body 1 k has a structure which in one chucking plane Ehas a chucking surface 1 u. This can be easily recognized in the crosssectional view according to FIG. 1b . When the nanostructure punch 5 ischucked onto the punch chucking apparatus 1, only the chucking surface 1u comes into contact with one chucking side 5 a of the nanostructurepunch 5. Opposite the chucking side 5 a is an embossing side 6 of thenanostructure punch 5.

The chucking surface 1 u of the chucking apparatus 1 is matched inparticular to the dimensions and peripheral contour of the nanostructurepunch 5. The especially UV-transparent nanostructure punch 5 can haveany shape, especially round, rectangular or square, preferably astandard wafer format.

The diameter of the nanostructure punch 5 preferably agrees largely withthe diameter of a substrate 7 which is to be embossed or is chosen to begreater than the diameter of the substrates. Preferably the diameter ofthe nanostructure punch 5 is at least the same size as the diameter ofthe substrate 7, more preferably the diameter of the nanostructure punch5 is larger by more than 5 mm, still more preferably the diameter of thenanostructure punch 5 is larger by more than 10 mm than the diameter ofthe substrate 7. The latter is preferably the case when the punchchucking apparatus 1 (nanostructure punch mount) is provided with vacuumtracks 4 outside an active embossing surface of the embossing side 6 inorder to achieve uniform embossing on the substrate 7. Preferably thenanostructure punch 5 projects over the substrate 7 by a maximum 50 mm.

The chucking surface 1 u in the embodiment according to FIGS. 1a and 1bis circular and a radius R_(u) of the chucking surface 1 u correspondsroughly to the radius of the substrates 7 to be embossed. The size ofthe chucking surface 1 u for the nanostructure punch 5 and of a chuckingsurface 2 u for the substrate 7 is preferably chosen to be the same sizeor slightly larger than the diameter of the substrate 7 and/or of thenanostructure punch 5. The diameters of the substrates 7 correspondpreferably to the diameters of 2″, 4″, 6″, 8″, 12″ or 18″ which areconventional in the semiconductor industry.

A radius R_(k) of the chucking body 1 k, as shown in the embodimentaccording to FIG. 1b , can be larger than the radius R_(u) of thechucking surface 1 u, especially by an annular shoulder section which isset back relative to the chucking surface 1 u.

Preferably only one outer ring section 9 of the chucking surface 1 u isintended for fixing of the nanostructure punch 5 by means of the vacuumtracks 4. The method of the invention is improved by the fixing of thenanostructure punch 5 taking place only in the region of the side edgeof the chucking surface 1 u. By reducing the negative pressure on thechucking surface 1 u the detachment from the nanostructure punch 5 canbe carried out in a controlled manner, especially from the ring section9. The ring section 9 of the chucking surface 1 u extends from theoutside contour of the chucking surface 1 u to the center of thechucking surface 1 u, especially in a width from 0.1 mm to 50 mm,preferably in a width from 0.1 mm to 25 mm. The ring section 9 extendsespecially in a width from 1/100 to ⅕ of the punch diameter, preferablyin a width of 1/50 to 1/10 of the punch diameter. In the exemplaryembodiment according to FIG. 1a the negative pressure is applied by avacuum apparatus (not shown) on two negative pressure channels or vacuumtracks 4 which run especially concentrically to one another.

In FIG. 1b the chucking surface 1 u according to the first embodiment ofthe punch chucking apparatus 1 is made blanketing or even (aside fromthe vacuum tracks 4).

According to another embodiment (FIG. 1c ) the chucking body 1 k′ of asecond embodiment of the punch chucking apparatus 1′ is set backrelative to the chucking plane E, especially within a chucking surface 1u′ so that at least one depression 18 is formed. In this way the supportsurface of the nanostructure punch 5, therefore the chucking surface 1u′, is made smaller compared to the embodiment according to FIG. 1a .The support surface according to one alternative embodiment can be madesmaller by honeycomb or circular depressions which are arrangedconcentrically to the center. The depth of the depression(s) 18 cancorrespond to the depth of the vacuum tracks 4 according to oneadvantageous embodiment.

The nanostructure punch 5 and optionally also other bordering componentsof the punch mount are preferably made of UV-transparent materials.

FIG. 2a shows a substrate chucking apparatus 2 of a device for chuckingof the substrate 7 on a chucking body 2 k. The chucking body 2 kaccording to one advantageous embodiment of the invention can be coated.The chucking body 2 k has the chucking surface 2 u which can be alignedparallel to the chucking plane E (FIG. 2b ).

The chucking surface 2 u of the chucking apparatus 2 is preferably atleast largely matched to the dimensions of the substrate. The chuckingsurface 2 u of the chucking apparatus 2 in the embodiment according toFIGS. 2a and 2b is circular and the radius R_(u) of the chucking surface2 u corresponds at least largely to the radius of the substrates 7. Thediameters of the substrates 7 correspond preferably to the diameters of2″, 4″, 6″, 8″, 12″ or 18″, preferably 18″ or larger, which areconventional in the semiconductor industry.

A radius R_(k) of the chucking body 2 k according to FIG. 2b can belarger than the radius R_(u) of the chucking surface 2 u. In theembodiment according to FIG. 2b the entire chucking surface 2 u isintended for fixing of the substrate 7 by means of vacuum tracks 4. Inthe exemplary embodiment according to FIG. 2a the negative pressure forfixing of the substrate 7 is applied by a vacuum apparatus (not shown)on several negative pressure channels or vacuum tracks 4 which cover thechucking surface 2 u and which run concentrically to one another.

In FIG. 2c the chucking surface 2 u′ according to a second embodiment ofthe chucking body 2 k′ is not made blanketing, but there is a depression19 which is set back relative to the chucking surface 2 u′, surrounded,preferably enclosed in particular by the chucking surface 2 u′. Thisdepression changes the support surface of the substrate 7 such that inparticular bilaterally structured or bilaterally processes substrates 7can be used. The support surface according to one alternative embodimentcan be made smaller by honeycomb or circular depression(s) 19 which arearranged concentrically to the center. The depth of the depression(s) 19can correspond to the depth of the vacuum tracks 4′ according to oneadvantageous embodiment.

FIG. 3a shows a substrate chucking apparatus 2″ of a device for chuckingan annular substrate 7′ (see FIG. 3c ) on a chucking body 2 k″ accordingto a third embodiment for a substrate 7′ with a hole 20 in the center ofthe substrate 7′. For example a hard disk is possible as the substrate7′ with a hole 20. A chucking surface 2 u″ of the chucking apparatus 2″is matched to the dimensions of the substrate 7″. The chucking surface 2u″ of the chucking apparatus 2″ in the embodiment according to FIGS. 3aand 3b is circular and a radius R_(u) of the chucking surface 2 u″corresponds largely to the radius of the substrates 7′.

According to FIG. 3b only one outer ring section of the chucking surface2 u″ covering roughly half the radius R_(u) is intended for fixing ofthe substrate 7′ by means of the vacuum tracks 4′. The substrate 7′ isthus fixed by a vacuum apparatus (not shown) by negative pressure onseveral negative pressure channels or vacuum tracks 4′ which runconcentrically to one another and which correspond to the entire annularsubstrate surface.

FIG. 4a shows another substrate chucking apparatus 2′″ of a device forchucking of the substrate 7′ on a chucking body 2 k′″ according to afourth embodiment for the substrate 7′ with a hole 20 (FIG. 3c ).

One chucking surface 2 u′″ for fixing of the substrate 7′ contains acore 2 h which projects relative to the chucking surface 2 u′″ and whichcorresponds especially to the hole 20. The core 2 h of the substratechucking apparatus 2′″ for substrates 7 can have different shapes, suchas for example round, cruciform, star-shaped, oval or angular. Theheight of the core 2 h corresponds especially to the thickness of thesubstrates 7′. The average thickness of the substrates 7′ is especiallybetween 20 and 10000 μm, preferably between 100 and 2000 μm, morepreferably between 250 and 1000 μm. The chucking surface 2 u′″ and thecore 2 h can have other dimensions so that other media can also befixed.

The chucking surface 2 u′″ of the chucking apparatus 2′″ in theembodiment according to FIGS. 4a and 4b is circular and a radius R_(u)of the chucking surface 2 u′″ corresponds largely to the radius of thesubstrates 7. In the embodiment according to FIG. 4b only one outer ringsection of the chucking surface 2 u′″ is intended for fixing of thesubstrate 7′ by means of vacuum tracks 4. In the exemplary embodimentaccording to FIG. 4b the substrate 7′ with the hole 20 is thus fixed bya vacuum apparatus (not shown) by negative pressure on two negativepressure channels or vacuum tracks 4 which run concentrically to oneanother and which cover the chucking surface 2 u on the outer ringsection.

FIG. 5a shows the chucking apparatus 1 (embodiment according to FIG. 1a) and 2 (embodiment according to FIG. 2a ) (also called chucks in thesemiconductor industry) of a device for chucking of the nanostructurepunch 5 and the substrate 7. The chucking apparatus 1 contains a centralopening 10 for routing of an actuator 3 (see also FIG. 1a ) or anactuator apparatus (not shown).

In a first embodiment of the invention the embossing process(nanoimprint process) is initiated with the actuator 3 in the center ofthe substrate. The actuator 3 can have different shapes and executions.Instead of an actuator pin, alternatively pressurization with a fluid ora gas as the actuator 3 is conceivable. The opening 10 for the actuator3 according to FIG. 1 can have different shapes and sizes.

FIG. 5b shows the device with the especially UV-transparentnanostructure punch 5 loaded onto the punch chucking apparatus 1. Thefixing of the nanostructure punch 5 (having nanostructure 13 formedthereon) takes place by a vacuum or negative pressure via the vacuumtracks 4 in the outer ring section of the punch chucking apparatus 1.

In the next process step according to FIG. 5c the substrate 7 is loadedonto the substrate chucking apparatus 2 and fixed by a vacuum ornegative pressure via the vacuum tracks 4′, a curable material 8 whichhas been applied to the substrate 7 with a punch surface 14 pointing up,therefore in the direction of the nanostructure punch 5. The substrate 7and the nanostructure punch 5 are kept separate during the evacuationand/or inert gas flushing process (therefore not yet in contact), thenanostructure punch 5 being arranged and aligned at the top with theembossing side 6 down and the substrate 7 at the bottom with the curablematerial 8 up.

FIGS. 6a to 6e show the process steps in a first embodiment of thedevice and of the method of the invention for a large-area nanoimprintprocess with a hard, UV-transparent nanostructure punch 5. The substrate7 and the nanostructure punch 5 are first aligned with high precisionfor an exact alignment and are kept separate during the evacuationand/or inert gas flushing process (FIG. 6a ).

As shown in FIG. 6b , a distance h between the substrate 7 andnanostructure punch 5 is reduced to an exactly defined distance h′before the nanoimprint process is started. Here the distance h′ isespecially less than 500 μm, preferably less than 250 μm, mostpreferably less than 100 μm, most preferably of all less than 50 μm.

By means of the actuator 3 the nanostructure punch 5 and the substrate 7make contact on a partial area 15 as much as possible in spots. Thecontact-making which is shown in FIG. 6c takes place by a concentricdeformation of the nanostructure punch 5 by the pressure which has beenapplied via the actuator 3, especially in the middle of thenanostructure punch 5. Here it is advantageous to apply a resultingforce F_(a) by triggering the actuator 3 or the actuator apparatus (notshown) in the center of mass of the surface of the nanostructure punch 5and thus in the center of mass of a contact surface between thesubstrate 7 and nanostructure punch 5.

After the first contact point has been reached, controlled reduction ofthe negative pressure causes release of the nanostructure punch 5 fromthe punch chucking apparatus 1, after which an embossing front 12propagates from the center especially concentrically, to the edge of thesubstrate 7 or the punch surface 14. The prestress which has beenapplied by means of deformation of the nanostructure punch 5 causescontact of the nanostructure punch 5 with the substrate 7 proceedingfrom the middle of the nanostructure punch 5 radially to the outside asfar as the periphery (see also FIG. 9a ). The remaining area 16 of thepunch surface 14 makes contact by the release.

FIG. 6e shows a completed embossing in which the embossing front 12 hasreached the edge of the substrate 7. The substrate 7 and thenanostructure punch 5 are in contact roughly over the entire area. Thenthe curing according to FIG. 8 can take place (see below).

FIGS. 7a to 7e show the process steps in a second embodiment of thedevice and of the method of the invention for large-area nanoimprintprocess with a hard, UV-transparent nanostructure punch 5. The substrate7 in this exemplary embodiment is the substrate 7′ according to FIG. 3c.

The substrate 7′ preferably has a diameter of 2.5 inches or 3.5 inches.The punch 7′ has a diameter of 4 inches or greater and is thus largerthan the substrate 7′. The chucking surface 1 u is formed in an outerring section of the chucking body 1 k for fixing of the nanostructurepunch 5 by means of vacuum tracks 4 (see FIG. 1b ). Thus the vacuumtracks 4 of the chucking surface 1 u are outside the active punchsurface 14 of the nanostructure punch 5. Since the substrate 7′ with thehole 20 has a smaller diameter than the nanostructure punch 5, thevacuum tracks 4 for holding the nanostructure punch 5 are outside of thepunch surface 14 which is to be embossed. The size difference is used tofix the nanostructure punch 5 by means of the vacuum tracks 4.

As FIG. 7b shows, the distance h between the substrate 7 and thenanostructure punch 5 is reduced to an exactly defined distance h′before the nanoimprint process is started. Here the distance h′ isespecially less than 500 μm, preferably less than 250 μm, mostpreferably less than 100 μm, most preferably of all less than 50 μm.

The contact-making which is shown in FIG. 7c takes place by concentricdeformation of the nanostructure punch 5 by the pressure which has beenapplied via the actuator 3 in the middle of the nanostructure punch 5.Here it is advantageous to apply a resulting force F_(a) by triggeringthe actuator 3 or the actuator apparatus (not shown) in the center ofmass of the surface of the nanostructure punch 5 and thus in the centerof mass of a contact surface between the substrate 7′ and nanostructurepunch 5.

Due to the center hole 20 of the substrate 7′ the contact surface is anannular partial area 15′ of the punch surface 14, the embossing front 12beginning at the edge of the hole 20.

After the annular contact-making has taken place, controlled reductionof the negative pressure of the vacuum tracks 4 causes release of thenanostructure punch 5 from the punch chucking apparatus 1. The prestresswhich has been applied by means of deformation of the nanostructurepunch 5 causes contact of the nanostructure punch 5 with the substrate7′ proceeding from the middle of the nanostructure punch 5 radially tothe outside as far as the periphery of the substrate 7′ (see also FIG.9a ). The remaining area 16′ of the punch surface 14 makes contact bythe release.

As soon as the nanostructure punch 5 has made contact with the edge ofthe hole 20, the embossing front 12 propagates concentrically toward theouter edge of the substrate. FIG. 7e shows a completed embossing front12. The substrate 7′ and the nanostructure punch 5, except for the hole20, are therefore in blanket contact on the entire punch surface 14.

FIG. 8 shows the wafer stack or substrate-punch stack at an unloadingstation and direct cross-linking of the curable material 8, especially aphotoresist, by means of UV light 11. More generally the curing can becarried out by electromagnetic radiation, by heat, by current, bymagnetic fields or other methods. Preferably the curing takes placethrough the transparent nanostructure punch 5. In another embodiment thecuring is carried out still in the imprint stage. Here curing takesplace through the transparent punch chucking apparatus 1, 1′ and throughthe transparent nanostructure punch 5.

Curing and separation of the nanostructure punch 5 from the substrate 7,7′ can take place directly in the imprint stage. Preferably theinstallation with the device of the invention has one module group witha common working space which can be sealed if necessary relative to theambient atmosphere. Here the modules, for example the resist applicationmodule, imprint module and unloading module can be arranged in a clusteror star configuration around a central module with one movementapparatus (robot system).

The method enables high-resolution structuring in the sub-micron range,preferably below 100 nm, more preferably below 50 nm, most preferablybelow 10 nm.

One alternative embodiment is shown in FIG. 9b . Here the nanoimprintprocess is initiated with an actuator 3, off-center, especially on thesubstrate edge, and the embossing front 12 propagates circularly fromthe contact point.

The propagation direction(s) of the embossing fronts 12 according to thefirst and second embodiments are compared schematically in FIGS. 9a and9b . Examples of the position of the actuators 3 are shown in FIGS. 9aand 9 b.

REFERENCE NUMBER LIST

-   1, 1′ punch chucking apparatus-   1 k, 1 k′ chucking body-   1 u, 1 u′ chucking surface-   2, 2′, 2″, 2′″ substrate chucking apparatus-   2 u, 2 u′, 2 u″, 2 u′″ chucking surface-   2 k, 2 k′, 2 k″, 2 k′″ chucking body-   2 h core-   3 actuator (pin)-   4 vacuum tracks-   4′ vacuum tracks-   5 nanostructure punch-   5 a chucking side-   6 embossing side-   7, 7′ substrate-   8 curable material-   9 ring section-   10 opening-   11 UV light-   12 embossing front direction-   13 nanostructure-   14, 14′ punch surface-   15, 15′ partial area-   16, 16′ remaining area-   17 embossing apparatus (especially consisting of punch chucking-   apparatus and nanostructure punch)-   18 depression-   19 depression-   hole-   A-A, B-B, C-C, D-D cutting line-   E chucking plane-   R_(u) ring radius-   R_(k) radius of the chucking body-   F_(a) force

Having described the invention, the following is claimed:
 1. A devicefor embossing of a nanostructure from a nanostructure stamp into a stampsurface of a substrate, comprising: one or more pressure elementsconfigured to prestress the nanostructure stamp during an imprintoperation and make contact of a partial area of the stamp surface of thesubstrate with the nanostructure stamp during the imprint operation. 2.The device of claim 1, wherein the pressure elements comprise one of afluid and a gas.
 3. The device of claim 1, further comprising: a forcesensor configured to control detachment of the nanostructure stamp andthe stamp surface of the substrate during a separation operation carriedout during the imprint operation.
 4. The device of claim 1, wherein thepressure elements comprise an actuator configured to mechanically bringthe nanostructure into contact with the partial area of the stampsurface of the substrate.
 5. The device of claim 1, wherein the pressureelements comprise a pin configured to mechanically bring thenanostructure into contact with the partial area of the stamp surface ofthe substrate.
 6. The device of claim 4, wherein the actuator ispressurized with a fluid.
 7. The device of claim 4, wherein the actuatoris pressurized with a gas.
 8. The device of claim 5, wherein the pin ispressurized with a fluid.
 9. The device of claim 5, wherein the pin ispressurized with a gas.